The Effects of Preirradiation and Postirradiation Temperature Treatments on the X-Ray Sensitivity of Seeds of Hordeum

Abstract

Dry (approximately 4% water content) seeds of Himalaya barley, when heated prior to irradiation, underwent little or no storage injury; also, the increase in injury due to aerobic hydration was as great 48 hours after irradiation as it was immediately thereafter. The effectiveness of preirradiation heat-treatments in reducing seedling injury depended on both the length of the heat-treatment and the temperature; it had no effect if hydration intervened between heating and irradiation. Postirradiation storage of seeds at elevated temperatures (75 deg C) caused an increase in injury over short storage periods but brought about a thermorecovery over longer storage periods. Preliminary experiments with acute postirradiation heat-treatments indicated that they, like preirradiation heat-treatments, decreased the amount of injury throughout the storage period. lrradiated seeds stored at dry ice temperature (- 78 deg C) showed virtually no increase in injury over long storage periods, and, as with preirradiation heat-treated seeds, they retained their sensitivity to aerobic hydration. The effects of preirradiation heat-treatment and postirradiation storage over a wide range of temperatures on the response of irradiated seeds to storage and to aerobic hydration, when combined with earlier work on these two parameters, suggest that they are alternative ways of magnifying a primarymore » radiation event. (auth)« less